A mitotic figure is a cell nucleus that is undergoing division. Mitosis has four phases: prophase, metaphase, anaphase, and telophase. Mitotic figure counting is one of three criteria (along with pleomorphism and tubularity) that is used for computing the Nottingham-Bloom-Richardson (NBR) grade. The count of mitotic figures per unit area of a human or animal tissue, provides information regarding how cancerous, if at all, the tissue is. The NBR grade is the standard malignancy grading for breast carcinoma. Usually, a trained pathologist counts mitotic figures manually, which is slow and expensive.
Digital pathology involves the use of computers to assist pathologists in grading tissue specimens. For example, a tissue sample for breast carcinoma diagnosis typically takes an expert five minutes or more to grade. Several studies have demonstrated low agreement among pathologists' grading of the same case, questioning the objectivity of their diagnosis. A successful system may assist the pathologist in diagnosis, helping to achieve more reproducible results at lower cost.
The prior art systems automatically detect and count mitotic figures by extracting certain simple features from figures. The figure are then classified as mitotic/non-mitotic by applying user-defined thresholds on the values of these features and then using Fisher's linear discriminant analysis. Unfortunately, the classification results produced by the prior art systems have not been reliable enough to allow the prior art systems to be used as an automatic diagnostic tool.
Accordingly, there remains a need for an apparatus/method for detecting and counting mitotic figures automatically and reliably.